{-|

> HetCATS/Utils.hs

> $Id$

> Authors: Klaus L�ttich

> Year: 2002

Useful functions that can't be found in the libraries.

But should shared across HetCATS.

Todo:

- Add your own functions.

-}

module Common.Utils where

import Data.List

import Common.AS_Annotation

{- |

A function inspired by perls join function. It joins a list of

lists of elements by seperating them with a seperator element.

-}

joinWith :: a -- ^ seperator element

-> [[a]] -- ^ list of lists of elements

-> [a]

joinWith sep = concat . intersperse (sep:[])

{- |

A function inspired by the perl function split. A list is splitted

on a seperator element in smaller lists. The seperator element is

dropped from the resulting list.

-}

splitOn :: Eq a => a -- ^ seperator

-> [a] -- ^ list to split

-> [[a]]

splitOn sep = (\(f,r) -> f : case r of

[] -> []

_ -> (splitOn sep $ tail r)

) . break ((==) sep)

{-|

A function inspired by a perl function from the standard perl-module

File::Basename. It removes the directory part of a filepath.

-}

basename :: FilePath -> FilePath

basename fp = (\(path,basen) -> basen) (stripDir fp)

{-|

A function inspired by a perl function from the standard perl-module

File::Basename. It gives the directory part of a filepath.

-}

dirname :: FilePath -> FilePath

dirname fp = (\(path,basen) -> path) (stripDir fp)

{-|

A function inspired by a perl function from the standard perl-module

File::Basename. It splits a filepath into the basename, the

directory and gives the suffix that matched from the list of

suffixes. If a suffix matched it is removed from the basename.

-}

fileparse :: [String] -- ^ list of suffixes

-> FilePath

-> (FilePath,FilePath,Maybe String)

-- ^ (basename,directory,matched suffix)

fileparse sufs fp = let (path,base) = stripDir fp

(base',suf) = stripSuffix sufs base

in (base',path,suf)

stripDir :: FilePath -> (FilePath,FilePath)

stripDir fp = (\(x,y) -> (reverse y, reverse x)) (break (== '/') (reverse fp))

stripSuffix :: [String] -> FilePath -> (FilePath,Maybe String)

stripSuffix suf fp = case filter justs $ map (stripSuf fp) suf of

[] -> (fp, Nothing)

((Just (x,s)):_) -> (x,Just s)

where stripSuf f s | s `isSuffixOf` f = Just (stripOf s f, s)

| otherwise = Nothing

justs (Nothing) = False

justs (Just _) = True

stripOf :: (Show a, Eq a) => [a] -> [a] -> [a]

stripOf suf inp = reverse $ stripOf' (reverse suf) (reverse inp)

where stripOf' [] i = i

stripOf' (x:xs) [] = error $

concat ["suffix is longer than input string\n"

,"input was: ", show suf, " ",show inp ]

stripOf' (x:xs) (y:ys) | x == y = stripOf' xs ys

| otherwise =

error $ concat ["suffix don't match input"

," at "

,show $ reverse (x:xs)

," ",show $ reverse (y:ys)]

-- stripOf suf = reverse . drop (length suf) . reverse

-- |

-- like the chomp from Perl

-- but this chomp removes trailing newlines AND trailing spaces if any

chomp :: String -> String

chomp = reverse . chomp' . reverse

where chomp' [] = []

chomp' xs@(x:xs') | x == '\n' || x == ' ' = chomp' xs'

| otherwise = xs

-- IgnoreMaybe datatype

-- extension to Maybe for use in computations over recursive types

-- that need a "don't care" result

--

-- RealJust a means result a was computed

-- RealNothing means computation failed

-- IgnoreNothing means the rest of the computation should not be

-- influenced by this result

--

data IgnoreMaybe a = RealJust a

| RealNothing

| IgnoreNothing

-- drop IgnoreNothing from a list to get Maybe list

--

dropIgnore :: [IgnoreMaybe a] -> [Maybe a]

dropIgnore [] = []

dropIgnore ((RealJust x):t) = (Just x):(dropIgnore t)

dropIgnore (RealNothing:t) = Nothing:(dropIgnore t)

dropIgnore (IgnoreNothing:t) = dropIgnore t

-- convert from Maybe to IgnoreMaybe

--

toIgnore :: Maybe a -> IgnoreMaybe a

toIgnore (Just x) = RealJust x

toIgnore _ = RealNothing

-- convert from IgnoreMaybe to Maybe

-- IgnoreNothing is propagated (wrt to the meaning given above) to Nothing

--

toMaybe :: IgnoreMaybe a -> Maybe a

toMaybe (RealJust x) = Just x

toMaybe _ = Nothing

-- map over IgnoreMaybe taking (Maybe a -> b) function

--

mapIgnore :: (Maybe a -> b) -> [IgnoreMaybe a] -> [b]

mapIgnore f [] = []

mapIgnore f (IgnoreNothing:t) = mapIgnore f t

mapIgnore f (h:t) = (f $ toMaybe h):(mapIgnore f t)

-- map over IgnoreMaybe taking (a -> b) function

--

mapIgnoreMaybe :: (a -> b) -> [IgnoreMaybe a] -> [b]

mapIgnoreMaybe f [] = []

mapIgnoreMaybe f (RealJust x:t) = (f x):(mapIgnoreMaybe f t)

mapIgnoreMaybe f (h:t) = mapIgnoreMaybe f t

-- add element to list as if it were a set

-- addition is to the front if element wasn't already in the list, in which

-- case the list is not modified

--

setAddOne :: Eq a => [a] -> a -> [a]

setAddOne set x = if (x `elem` set) then set else (x:set)

-- concat two lists as if they were sets

-- adds each element from the second list using setAddOne

--

setAdd :: Eq a => [a] -> [a] -> [a]

setAdd set add = foldl setAddOne set add

-- find out whether all the elements of a list occur only once

--

allUnique :: Eq a => [a] -> Bool

allUnique [] = False

allUnique [h] = True

allUnique (h:t) = ([ x | x<-t, x == h ]==[]) && allUnique t

-- compute members of a list occuring more than once

--

notUnique :: Eq a => [a] -> [a]

notUnique [] = []

notUnique (h:t) = let

diff = [ x | x<-t, x/=h ]

rest = notUnique diff

in

case (h `elem` t) of True -> h : rest;

False -> rest